### Why are the changes needed?
<img width="1860" height="908" alt="image" src="https://github.com/user-attachments/assets/ec445237-be62-405f-992e-56e10156407f" />
**Current Behavior:**
When "kyuubi.engine.share.level = USER/GROUP/SERVER", the first client (Client A) calling openSession creates a Kyuubi-Spark-SQL-Engine (Spark Driver), where the initialization SQL configured in "kyuubi.session.engine.spark.initialize.sql" takes effect.
Subsequent clients (e.g., Client B) connecting via openSession will reuse the existing Kyuubi-Spark-SQL-Engine (Spark Driver) created in step 1, where the initialization SQL configured in "kyuubi.session.engine.spark.initialize.sql" becomes ineffective.
**Why This Capability Is Needed:**
Currently, kyuubi.session.engine.spark.initialize.sql only applies to the first openSession client. All subsequent SQL operations inherit the initialization SQL configuration from the first client (this appears to be a potential bug).
Client A may need to set "USE dbA" in its current SQL context, while Client B may need "USE dbB" in its own context - such scenarios should be supported.
### How was this patch tested?
Tested on local Kyuubi/Spark cluster. No existing unit tests cover this scenario. Please point me to any relevant tests so I can add them
### Was this patch authored or co-authored using generative AI tooling?
No
Closes#7138 from 1358035421/lc/spark_session_init_sql.
Closes#7138
338d8aace [Cheng Pan] remove dash
1beecc456 [Cheng Pan] fix
6c7f9a13e [liangzhaoyuan] update migration-guide.md
492adb6c4 [liangzhaoyuan] fix review comments
f0e9320be [1358035421] Merge branch 'master' into lc/spark_session_init_sql
021455322 [liangzhaoyuan] update migration-guide.md
b4e61cf89 [liangzhaoyuan] ut
ca4c71253 [Cheng Pan] Update externals/kyuubi-spark-sql-engine/src/main/scala/org/apache/kyuubi/engine/spark/session/SparkSQLSessionManager.scala
da92544f1 [liangzhaoyuan] fix
c1a38d584 [liangzhaoyuan] Support executing kyuubi.session.engine.spark.initialize.sql on session initialization
Lead-authored-by: liangzhaoyuan <lwlzyl19940916@gmail.com>
Co-authored-by: Cheng Pan <chengpan@apache.org>
Co-authored-by: 1358035421 <13588035421@163.com>
Co-authored-by: Cheng Pan <pan3793@gmail.com>
Signed-off-by: Cheng Pan <chengpan@apache.org>
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